Last month I detailed the 1 Upper Body Exercise to Stop Right Now, and now its time to stop the insanity with the legs as well. This time I am giving you two exercises. Now, let me preface this with one detail: If you have ever competed in bodybuilding or have already paid your entrance fee to compete, then you get a pass. I understand the need to isolate muscles for a competition. This list is simply for the person working out to get in shape, get stronger, or just to be healthy. Alright, let’s get started.
#1: The Knee Extension Machine
This is the reason I am giving you two, because this one showed up as an example during my previous post. This machine is great for my career as a physical therapist, not great for your knees.
Mechanism: Works in an open-chain environment, which in this case means you are not bearing weight through the foot. When you work the quads in open-chain the quad tendon and patellar tendon work as a pulley over your patella (knee cap). During the knee extension exercise research shows a significant increase in joint reaction force and joint stress.
Advantages: Hypertrophy? Not really, research does show increased rectus femoris activity with knee extensions, the squat showed better recruitment of hamstrings, overall quads, glutes, and a better functional carryover with steps.
Disadvantages: Imagine you are Eazy E crusin’ down the street in your 6-4, then over time your tires, wheels, and axles fall off the car. Do you hear that screeching, grinding sound? Yeah, that’s what the back of your kneecap sounds like during the knee extension machine.
Reason to use: Can’t think of a great one.
#2 Seated Calf (soleus) raises
Muscle: Mostly Soleus
Mechanism: By bending the knee you reduce the force the gastrocnemius can generate. The gastrocnemius is a two-joint muscle which means it crosses two joint lines: Knee and Ankle. The soleus on the other hand crosses only one joint the ankle therefore with the knee eliminated, the soleus is left to take the brunt of the force.
Advantages: Isolating the soleus can be advantageous for overall calf development. Research has shown that the soleus contains significantly more slow twitch muscles fibers than the gastrocnemius. Therefore, with the distance running population, it can be theorized that development of the soleus can help.
Disadvantages: The isolation, while good for distance runners in theory can also create a significant reduction in ankle dorsiflexion (see picture).
A reduction of dorsiflexion can create a loss of efficiency with step length and force absorption in walking and running. Over time this can cause a breakdown in the feet, knees, and hips. In addition, trigger points in the soleus can mimic Achilles tendonitis pain.
In both cases there are better exercises to do for functional gain, and the increased risk of injury isn’t worth the effort.